Tree shrews (Tupaia belangeri chinenesis) can be experimentally infected with human hepatitis B virus (HBV) by inoculation with human serum positive for HBV, the experimental infection rate being 55.21%. Successive infections have been passed through five generations among the tree shrews inoculated with HBV-positive sera from the infected animals, the average infection rate being 94.0%. The experimental infection of tree shrews with HBV may be prevented by immunization with hepatitis B vaccine, the protection rate being 88.89%. Standard serum containing HBV at 10(8) CID (chimpanzee infection dose)/ml, was diluted 10(-6), 10(-7), 10(-8), 10(-9), and 10(-10) and produced infection rates of 80.0%, 88.8%, 66.7%, 55.6% and 42.9% respectively. Thus the CID50 in tree shrews may reach a dilution of 10(-9), which shows that tree shrews are sensitive to HBV infection. These results successfully establish tree shrews as a reliable and useful animal model for research on HBV infection and its relation to hepatocarcinogenesis.

We report a typical case of hematidrosis in a Chinese girl who had experienced frequent bleeding episodes for more than 3 years. During hospitalization, spontaneous bleeding from her intact skin was witnessed by our staff on more than 20 occasions. Characteristically, bloody droplets from the intact skin contained all blood components. Histopathologic examination showed some inconspicuous abnormalities, with normal sweat gland structure containing no blood, and bloody exudate also came from some areas that do not contain sweat glands. We believe that the blood was mixed with a sweat-like fluid, rather than real sweat. The patient's bleeding problem was dramatically resolved by treatment with propranolol. We suggest that sympathetic nerve activation might play a role in these events, and that β-adrenoceptor antagonists might be an effective treatment for this disorder.

No abstract

On the basis of the successful establishment of an animal model in tree shrews experimentally infected with human hepatitis B virus (HBV), a study on the hepatocarcinogenic effects of HBV and/or aflatoxin B1 (AFB1) was conducted. The results showed that the incidence of hepatocellular carcinoma (HCC) was significantly higher in the animals both infected with HBV and exposed to AFB1 (52.94%) than in those solely infected with HBV (11.11%) or exposed to AFB1 (12.50%). No HCC of precancerous lesions were found in the controls that were neither HBV-infected nor AFB-1 exposed. Precancerous lesions, including liver cell dysplasia and enzyme-altered hyperplastic hepatocyte foci, were observed before the occurrence of HCC, and the frequency of their appearance correlated well with the incidence of HCC. HBV DNA and the protein it encodes were detected in the cancer cells and/or the surrounding hepatocytes. Integration of HBV DNA into the host liver genome was found during hepatocarcinogenesis among the animals infected by HBV. These results suggest that exposure to HBV and AFB1 may play a synergistic role in the development of HCC, and support the viewpoint of an aetiological relationship between HBV and HCC.

Around the world, climate change has impacted many species. In this study, we used bioclimatic variables and biophysical layers of Central Asia and the Asian Highlands combined with presence data of brown bear (Ursus arctos) to understand their current distribution and predict their future distribution under the current rate of climate change. Our bioclimatic model showed that the current suitable habitat of brown bear encompasses 3,430,493 km2 in the study area, the majority of which (>65%) located in China. Our analyses demonstrated that suitable habitat will be reduced by 11% (378,861.30 km2) across Central Asia and the Asian Highlands by 2,050 due to climate change, predominantly (>90%) due to the changes in temperature and precipitation. The spatially averaged mean annual temperature of brown bear habitat is currently −1.2°C and predicted to increase to 1.6°C by 2,050. Mean annual precipitation in brown bear habitats is predicted to increase by 13% (from 406 to 459 mm) by 2,050. Such changes in two critical climatic variables may significantly affect the brown bear distribution, ethological repertoires, and physiological processes, which may increase their risk of extirpation in some areas. Approximately 32% (1,124,330 km2) of the total suitable habitat falls within protected areas, which was predicted to reduce to 1,103,912 km2 (1.8% loss) by 2,050. Future loss of suitable habitats inside the protected areas may force brown bears to move outside the protected areas thereby increasing their risk of mortality. Therefore, more protected areas should be established in the suitable brown bear habitats in future to sustain populations in this region. Furthermore, development of corridors is needed to connect habitats between protected areas of different countries in Central Asia. Such practices will facilitate climate migration and connectivity among populations and movement between and within countries.